Process for the manufacture of artificial textile fibers



cause otherwise the colloidal solution would lose its spinningproperties.

Patented Jan. 11, 1944 PNITED TATE-S, PATE T 1 oer-lea assault PROCESSFOR ABTIF! OIAL mm FIBERS Antonio mm, Milan, Italy; vested in the AlienProperty Custodian no Drawlhg. Application July 31, 1940, Serial No.348,993. In Italy August as, 1935 6 Claims.

This invention concerns improvements in or relating to processes for themanufacture of artificial textile fibers.

A process is described in co-pending U. S. patent application Serial No.96,470, filed August '17, 1936 (and in Italy August 28, 1935), by whichcasein may be produced which is suitable for use in the manufacture ofartificial textile fibers. This application is a continuation in part ofsaid copending application. Casein, however delivered, is soluble in allalkalies giving viscous colloidal solutions. The present inventionprovides in a process for the manufacture 'of artificial textile fibersthe selection or sodium hydrate and/or potassium hydrate as solvents forcasein in the production of a colloidal solution thereof. Hitherto theweaker alkalies such as sodium borate,

.sodium carbonate and ammonium hydrate have been employed for thispurpose because they do not affect the casein. ,According to the presentinvention, however, sodium hydrate and/or 'potassium hydrate areselected from all known alkalies for the production of a colloidalsolution of casein although they have hitherto been avoided because theyattack casein more than any other alkalies. All other alkaline agents,even it combined together in the most varied proportions, producecolloidal solutions of casein which cannot be spun. This fact, which hasbeen ascertained as the result of numerous experiments, applies not onlyto the textile casein produced by the process described and claimed inthe specification of the patent application referred to above, but toall trade caseinswhether lactic or acid. Thus despite the disadvantagesnormally associated with sodium hydrate and potassium hydrate, onlythese two alkaline agents can be employed, according to the presentinvention, for the production of a colloidal solution of casein suitablefor use in the manufacture of artificial textile fibers. I

In practice it is preferable to employ sodium hydrate because it ischeaper than potassium hydrate while the results are identical. Amixture of sodium hydrate and potassium hydrate can also be used. Also,small quantities 0! other alkaline agents may be added to the solutionin order to modify slightly the properties of the colloidal solution. Itis necessary, however, to conthis these. additions within narrow limits,be-

In other words, it is essential that the alkaline agent employed for thecolloidal solution of casein should alkali are employed in theequivalent ratio of 23 litres of 35 B. sodium hydrate to 100 kilogrammesof dry unwashed caseincontaining a normal quantity of moisture, with atolerance on the quantity of alkali employed of 20% above or below theindicated value.

The amount of sodium hydrate preferably to be employed in order toobtain a colloidal solution of casein suitable for the manufacture oftextile fibers has been calculated upon the assumption that atemperature of 24 C. is employed forthe solution of the casein and forits subsequent maturing. However, the amount 0! sodium hydrate may beslightly reduced if the adopted temperature is higher than thetemperature indicated above, and conversely the amount maybe slightlyincreased for a lower temperature. No true reverse proportion, however,exists between the quantity of alkali andthe temperature adopted,

because the quantity of alkali generally'infiuences the solubility ofthe casein, whereas the temperature generally influences the viscosity,

volume and maturing of the colloidal solution.

pared with 'the viscosity necessary for spinning and, above all, therisk of seriously endangering the quality or the ultimate product isincurred. Conversely, with a temperature below 14 C., an undulylarge anduseless delay occurs in the maturing and it is-difiicult, if notimpossible, to

realise the desired volume or colloidal solution.

ofcasein It is possible to increase the viscosity of the colloidalsolution of casein without altering its spinning property (and evenimproving the same) by employing special diluting agents hereinafterspecified. These diluting agents, however, always have the same eflectupon the viscosity and the volume of the colloidal solutions whatevermay have been the preparation and maturing temperatures, so that thedifferences of the colloidal solutions of the textile casein inviscosity and volume remain practically unaltered relatively'to oneanother at the different temperatures.

Example A When a .dried casein that has not been washed aftercoagulation is employed:

A predetermined quantity of dried and ground casein is placed in asuitable vessel fitted with a stirring device and with a double bottomand double walls for the circulation of the water necessary to regulatethe temperatures during the dissolving, diluting and maturing of thecolloidal solution of casein.

For each 100 kilos oi dried casein containing a normal moisturepercentage of 200 litres of water previously heated to a temperature of24 C. are poured into the vessel, and uniformly distributed throughoutthe casein which has been previously placed in the vessel. However, itis also practicable to pour the water into the vessel before the caseinhas been introduced.

After the water and casein have been mixed for two or three hours thereis introduced into the vessel a solution comprising 23 (twenty three)litres of 35 B. sodium hydrate and 77 (seventy seven) litres of water,previously heated to a temperature of 24 C. for each 100 kilos of driedcasein referred to above. The solution is energetically stirred in orderrapidly and uniformly to incorporate the sodium hydrate with the caseinsolution. When the mixture has become uniform the stirring may be sloweddown or be effected only at intervals. The temperature is preferablymaintained constant at 24 C. It may be mentioned that instead ofemploying prepared 35 B. sodium hydrate, a corresponding quantity of drysodium hydrate may be dissolved in water. Likewise, the procedure is thesame if instead of sodium hydrate, potassium hydrate is employed,bearing in mind that, the temperature of 24 C. remaining unaltered, thequantity used must correspond to the alkalinity or neutralizing power of23 litres 35 B. sodium hydrate for each 100 kilos of dry caseincontaining 10% moisture. If the moisture percentage in the caseinemployed is higher or lower, the amount of water and alkali to be addedto the casein must be varied accordingly.

When the casein has been dissolved and the mass has gradually becomemore viscous (this being eflfected in a few hours depending upon thetype of casein employed, namely, whether it has been coagulated with agreater or smaller quantity of acid, and a temperature of 24 C. hasremained unaltered), a slow and gradual dilution is effected so as tocompensate for the increasing viscosity of the colloidal solution whilstit matures.

The diluting agents hereinafter specified and previously, heated to atemperature of 24 C. are preferably added little by little in order toavoid momentarily an unduly great dilution which would delay the regularand gradual development of the viscosity necessary to permit thesubsequent additions of diluting agents until the desired volume of thecolloidal solution is obtained and without causing this solution to loseits spinning property.

When the desired volume and viscosity of the colloidal solution havebeen obtained, the increase in the viscosity can be stopped by slightlylowering the temperature of the solution, the solution thus remainingstabilised for a certain time so that it can be transferred to thespinning machines with the properties and characteristics previouslyestablished. This is of the greatest importance for regularspinningwhich otherwise would be dlilicult to obtain.

The time necessary for accomplishment of the above features, that is thetime required for the dissolving, the maturing and the increasing ofvolume of the colloidal solution of casein may vary within wide limits,because .the said time does not depend solely upon the desired volumeand viscosity but also upon the types of the case'- lns, anddilutingagents that are employed and upon the temperature employed during thealkaline-dissolving and maturing of the casein.

A casein obtained from 250 cubic centimetres of 66 B. sulphuric acid foreach litres of skimmed milk by the methods described above, dissolved inthe manner indicated at a. constant temperature oi 24 C., and dilutedwith ordinary water, generally takes 48 hours to mature in order toreach a viscosity suitable for spinning and a volume of 550-800 litresfor each 100 kilos dry casein used. When a smaller volume is desired,allother factors remaining unaltered, the time for maturing may bereduced somewhat. Whena greater volume is desired, the time for maturingmay be increased but only up to a certain limit because it has beenfound that after 96 hours, for instance it is possible detrimentally toeffect the quality of the textile ilbers obtained.

Also the quantity of acid employed for coagulation of the casein, and toa slight extent also the types of acid employed, play an important partin determining the viscosity and volume of the alkaline solution ofcasein. The greater the amount of the acid employed for coagulatingcasein, the viscosity and volume of the subsequent alkaline colloidalsolution are lower and are obtained less rapidly. Conversely, thesmaller the quantity of acid employed so the viscosity and volume of thesolution are higher and are obtained more rapidly. By an excessivevariation of the quantity of acid in the one or in the other direction,solutions can be obtained which are diillcult to spin, apart from thelower quality of the resulting fibers.

Accordingly, when caseins having the diflerent propertie indicated aboveare employed, it is preferable andin the extreme cases mentionedessential-to modify the initial volume of casein solution.

In the example indicated above the initial volume after the addition ofthe sodiumhydrate solution is 400 litres for each 100 kilos of caseinemployed. This volume may be slightly increased or reduced, but onlybetween narrow limits because by increasing the volume by a greateraddition of water, while the other factors remain unaltered, thecomplete dissolving of the casein and the development of the viscosityrequisite for proceeding to the successive additions of diluting agentare delayed. If an excessive initial volume of casein solution isemployed, the regular development of the process may be irreparablyspoiled. On the other hand, a reduction of the initial volume of caseinsolution renders an intimate mixture of the alkali and volume of caseinsoluacid it is advisable to the casein, and

of the initial solution, and conversely to increase the same for caseinsthat have been coasulated with a smaller quantity or acid.

The casein that has been washed prior to drying is dissolved in the samemanner as that which has not been washed, with the difierence that thequantity of alkali employed is reduced according to the lesser quantityof acid left in the casein in consequence of washing.

Example B The dissolving of casein which has not been dried, that is tosay, casein which still contains a percentage of acid serum, is carriedinto effect with the'following modifications.

The casein, coagulated and heated in its serum as indicated above andpreviously deprived of its excess moisture, is pressed so as to reduceits serum content, preferably to less than 200% of the weight of the drycasein, this being effected in order to facilitate the subsequentgrinding of the pressed casein.

The casein is placed in a vessel constructed as previously described,without addition of water which in this case is replaced by the serumleft in the casein. The 35 B. sodium hydrate solution is then added,this solution having been previously diluted with the quantity of waternecessary to produce, as indicated in the preceding ex-- ample, a volumeof 400 litres for each 100 kilos of casein, always referred to the dryweight of casein including the norma1 moisture content of the procedurethereafter is the same as that indicated in Example A.

In order to increase the volume of the solution while maintaining theviscosity constant the solution is diluted during the maturing action,for example by means of the milk serum obtained after the coagulation ofthe casein or by a solution of sodium lactate, or sodium formate orsodium bisulphite or soap.

Substances of the type of sulphides and xanthogenates which acceleratethe subsequent coagulating properties of the casein may be added to thealkaline solution. A suitable accelerating agent is carbon disulphide orsodium sulphide, or sodium sulphohydrate. Soaps, glycerine and the like,previously'treated with carbon sulphide and sodium hydrate, or cellulosexanthogenate can be employed.

The colloidal solution of casein obtained by the process according tothe present invention is suitable for spinning in the manufacture ofartificial textile fibers.

what I claim and desire to secure by United States Letters Patent is:

1. In the process of manufacturing artificial ing the same the stepscomprising the treatment of the acid casein by maturating it in anaqueous solution of an alkali selected from the group consisting ofsodium and potassium hydrates, under a temperature within the range 14to 34 C., and controlling the progressive growth of viscosity withmaturation by substantially increasing the volume of solution by addingan aqueous diluent.

2. The process as defined in claim 1 wherein carbon sulphide is added tothe casein solution before spinning, adapted to accelerate thesubsequent coagulation of filaments.

3. In a process for manufacturing textile fibers from casein, the stepof dissolving and maturating the casein preparatory to spinning andcoagulating filaments therefrom and insolubilizing the same,characterized in that the casein is dissolved and maturated in anaqueous alkaline solvent containing an alkali selected from the groupconsisting of sodium hydrate and potassium hydrate,

' in the proportion of casein in solution, the equivaning of filamentsand coagulating and insolubilizlent of about kilograms of dry casein,and of alkali, the equivalent of 19 to 2'7 liters of sodium hydrate 35B.; and controlling the growth of viscosity during maturation byprogressively diluting the solution by a watery diluent.

4. In a process for manufacturing textile fibers from casein bydissolving and maturating' the casein preparatory to spinning andcoagulating filaments therefrom and insolubilizing the same,characterized in that the casein is dissolved and maturated in anaqueous alkaline solvent containing in preponderance an alkali selectedfrom the group consisting of sodium hydrate and potassium hydrate, andthere is an increase in viscosity during maturation the steps ofprogressively diluting the solution by a watery diluent to asubstantially increased volume and regulating the viscosity bymaintaining a maturating temperature of between about 14 and 34 C., witha .higher temperature for accelerated maturation and greater viscosityor volume.

5. In the process of manufacturing artificial textile fibers fromacidified milk casein, by spinning of filaments and coagulating andinsolubilizing the same the steps comprising the treatment or the acidcasein by maturating it in an aqueous alkaline solution preponderatelyof sodium hydroxide, under a temperature in the general vicinity of 24C. and controlling the progressive growth of viscosity with maturationby substantially increasing the volume of solution by adding.

an aqueous diluent.

6. The process as defined in claim 5 wherein to accelerate filamentcoagulation after spinning, the casein solution before spinning isprovided with a sulphide coagulation-accelerating agent.

monro mam

